Immunoglobulins

Test Overview

An immunoglobulins test is done to measure
the level of immunoglobulins, also known as
antibodies, in your blood.

Antibodies are
substances made by the body's
immune system in response to bacteria, viruses,
fungus, animal dander, or cancer cells. Antibodies attach to the foreign
substances so the immune system can destroy them.

Antibodies are specific to each type of foreign
substance. For example, antibodies made in response to a
tuberculosis infection attach only to tuberculosis
bacteria. Antibodies also work in allergic reactions. Occasionally, antibodies
may be made against your own tissues. This is called an
autoimmune disease.

If your immune system makes low levels of antibodies, you may have a greater chance of
developing repeated infections. You can be born with an immune system that
makes low levels of antibodies, or your system may make low levels of
antibodies in response to certain diseases, such as cancer.

The
five major types of antibodies are:

IgA. IgA antibodies are found in areas of the body
such the nose, breathing passages, digestive tract, ears, eyes, and vagina. IgA
antibodies protect body surfaces that are exposed to outside foreign
substances. This type of antibody is also found in saliva, tears, and blood.
About 10% to 15% of the antibodies present in the body are IgA antibodies. A
small number of people do not make IgA antibodies.

IgG. IgG antibodies are found in all body fluids.
They are the smallest but most common antibody (75% to 80%) of all the
antibodies in the body. IgG antibodies are very important in fighting bacterial
and viral infections. IgG antibodies are the only type of antibody that can
cross the
placenta in a pregnant woman to help protect her baby
(fetus).

IgM. IgM antibodies are the largest antibody. They
are found in blood and lymph fluid and are the first type of antibody made in
response to an infection. They also cause other immune system cells to destroy
foreign substances. IgM antibodies are about 5% to 10% of all the antibodies in
the body.

IgE. IgE antibodies are found in the lungs, skin,
and mucous membranes. They cause the body to react against foreign substances
such as pollen, fungus spores, and animal dander. They are involved in allergic
reactions to milk, some medicines, and some poisons. IgE antibody levels are
often high in people with allergies.

IgD. IgD antibodies are found in small amounts in
the tissues that line the belly or chest. How they work is not clear.

The levels of each type of antibody can give your
doctor information about the cause of a medical problem.

Check the response to immunizations to see if you are
immune to the disease.

Check to see if you have an infection or have had it in the past.

This test is often done when the results of a blood protein
electrophoresis or total blood protein test are abnormal.

How To Prepare

You do not need to do anything before
you have this test.

How It Is Done

The health professional drawing blood
will:

Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.

Clean the needle site with
alcohol.

Put the needle into the vein. More than one needle stick
may be needed.

Attach a tube to the needle to fill it with
blood.

Remove the band from your arm when enough blood is
collected.

Put a gauze pad or cotton ball over the needle site as
the needle is removed.

Put pressure on the site and then put on a
bandage.

How It Feels

The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
pinch.

Risks

There is very little chance of a problem from
having a blood sample taken from a vein.

You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for several
minutes.

In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.

Results

An immunoglobulins test is done to
measure the level of immunoglobulins, also known as
antibodies, in your blood.

Normal

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

The
results listed below are normal values for adults. Children have different
values than adults. Results are ready in several days.

IgG. High levels of IgG may mean a long-term
(chronic) infection, such as
HIV, is present. Levels of IgG also get higher in IgG
multiple myeloma, long-term hepatitis, and
multiple sclerosis (MS). In multiple myeloma, tumor
cells make only one type of IgG antibody (monoclonal); the other conditions
cause an increase in many types of IgG antibodies (polyclonal).

IgM. High levels of IgM can mean
macroglobulinemia, early viral hepatitis,
mononucleosis, rheumatoid arthritis, kidney damage
(nephrotic syndrome), or a
parasite infection is present. Because IgM antibodies
are the type that form when an infection occurs for the first time, high levels
of IgM can mean a new infection is present. High levels of IgM in a newborn
mean that the baby has an infection that started in the
uterus before delivery.

IgD. How IgD works in the immune system is not
clear. A high level may mean IgD multiple myeloma is present. IgD multiple myeloma is much
less common than IgA or IgG multiple myeloma.

IgE. A high level of IgE can mean a parasite
infection is present. Also, high levels of IgE often are found in people who have
allergic reactions,
asthma,
atopic dermatitis, some types of cancer, and certain
autoimmune diseases. In rare cases, a high level of IgE may mean IgE multiple
myeloma.

Low values

IgA. Some people are born with low or absent
levels of IgA antibodies. Low levels of IgA occur in some types of
leukemia, kidney damage (nephrotic syndrome), a
problem with the intestines (enteropathy), and a rare inherited disease that
affects muscle coordination (ataxia-telangiectasia). A low level of IgA increases the
chance of developing an autoimmune disease.

IgG. Low levels of IgG occur in
macroglobulinemia. In this disease, the high levels of IgM antibodies stop the
growth of cells that make IgG. Other conditions that can cause low levels of
IgG include some types of leukemia and a type of kidney damage (nephrotic
syndrome). In rare cases some people are born with a lack of IgG antibodies.
These people are more likely to develop infections.

IgM. Low levels of IgM occur in multiple myeloma,
some types of leukemia, and in some inherited types of immune diseases.

What Affects the Test

Reasons you may not be able to
have the test or why the results may not be helpful include:

Taking certain medicines. Be sure your doctor knows all of the medicines you take. Some medicines that affect test results include ones used for birth control, heart failure, seizures, and rheumatoid arthritis.

What To Think About

Immunoglobulins are made specific to different
illnesses. For example, the
IgM antibody for mononucleosis is different than the
IgM for
herpes. For this reason, a doctor can look for an
immunoglobulin to a specific illness to help diagnose that
illness.

Different antibodies can be used to help a doctor tell the
difference between a new and past infection. For example, IgM antibodies for
mononucleosis with or without IgG antibodies means a new mono infection. IgG
antibodies without IgM means a past mono infection.

People with
very low immunoglobulin levels, especially IgA, IgG, and IgM, have a higher
chance of developing an infection.

A very small number of people
cannot make IgA and have a higher chance of developing a potentially
life-threatening reaction to a blood transfusion.

An immunoglobulin
test is often done when the results of a blood protein electrophoresis or total
blood protein test are abnormal.

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